recursive template expansion: Why does this not compile?

[Ontonator]

On Wednesday, 21 March 2018 at 06:39:22 UTC, ag0aep6g wrote:
> On 03/21/2018 01:47 AM, Ontonator wrote:
>> The following code does not compile:
>>> [...]
>> 
>> It gives the error:
>>> [...]
>> 
>> The aliases do not have to be aliases, as long as there is 
>> some reference to the class (e.g. method and variable 
>> declarations also work). What exactly is the reason for this 
>> error?
>
> Compiler bug. It works when you move the declaration of `B` 
> before the one of `A`. Order shouldn't matter there.

Is this a known bug, or should I report it?